This invention relates generally to digital data apparatus and more particularly to digital data apparatus which reads and expands compressed digital data contained on datastrips.
Microprocessor controlled equipment utilizing digital data have become commonplace in industry, in business and in the home. In some equipment (such as the microwave oven, or other consumer appliances), programming of the microprocessor is dedicated to the specific control of the equipment. Thus, the microprocessor is not independently programmable by the equipment user. In other equipment (such as home or personal computers), the microprocessor is the heart of a digital data system which may be independently programmed by the user.
Major obstacles to the wider acceptability of user programmable digital data utilization apparatus have been the skill and time required to learn to use such apparatus. Moreover, available software often is expensive (costing several hundred dollars or more), and requires considerable time and effort to master the terminology and routines presented in the software. Typically, the home or personal computer includes a floppy disc drive. The software to be utilized in the computer is encoded on a floppy disc which is inserted into the floppy disc drive of the computer. Although versatile, such a programming system is expensive and requires skill to implement.
Other systems have been proposed for making microprocessor controlled apparatus more flexible and capable of performing a variety of functions through the use of interchangeable keyboard overlays, digital cartridges and the like. (See, for example, U.S. Pat. Nos. 4,439,757 and 4,119,839) Such systems are disadvantageous because, by separating the keyboard overlay from the data cartridge, one or the other may be lost, rendering the system useless. Moreover, the data cartridges or cassettes are expensive.
Another system which has been proposed for increasing the versatility of digital data apparatus is to provide a dedicated keyboard with a limited number of keys, but to store within the apparatus, software programming for different functions for each key relating to several different applications. Interchangeable keyboard overlays are then placed over the keyboard to provide visual indicia of the functions of the keys for a specific application. The keyboard overlays may also include machine readable codes or memory chips. These systems have limited flexibility and are costly and complex. (Such systems are disclosed, for example, in U.S. Pat. No. 3,158,317 entitled CONTROL DEVICE, issused Nov. 24, 1964; U.S. Pat. No. 3,560,964 entitled KEYBOARD UNIT, issued Feb. 2, 1971; and U.S. Pat. No. 4,279,021 entitled PROTABLE DATA ENTRY APPARATUS INCLUDING PLRUAL SELECTABLE FUNCTIONAL CONFIGURATIONS, issued Jul. 14, 1981)
Another programming system is disclosed in U.S. Pat. No. 4,631,700, entitled MAGNETICALLY CODED SOFTWARE FOR MULTIPURPOSE COMPUTER, issued Dec. 23, 1986, filed Aug. 11, 1983. As disclosed in this patent, a computer keyboard matrix overlay panel includes magnetic and optical datastrips which contain data program steps and subroutines which are read into the digital data device by a reader. In digital data apparatus which are programmable by means of digital data rad from magnetic or optical datastrips contained on replaceable keyboard overlays or the like, it is desirable that the amount of digital data contained in a datastrip be maximized. Thus, more complex programs or larger amounts of data can be provided to the digital data apparatus. It is also desirable that the time required to read the data into the apparatus be minimized, so that the digital data read into the apparatus can be ready for use as quickly as possible.